Concentrating apparatus.



No. 744.823. vPATBIWED Nov. 24, 190s. G. R. TUCKER a. G. W. GODDARQGONUENTRATING APPARATUS.

APPLICATION FILED MAY 27, 1901. RBNEWBD ooTzo, 190s.

lA// TNA-S555 0.0mm Wm No. 744,823. PATENTED Nom-24, 1903. G. R. TUCKERA. G. W. GUDDARD.

CONGENTRATING APPARATUS.

APPLICATION FILED MAY 27, 1901. RIEIIQTEWED 00T. 20. 1903.

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No. 744,823. PATBN'TED Nov. 24, 1903. G. 11. TUCKER a. G. W. GODDARD.

GONCENTRATING APPARATUS. APPLIOATIONPILBD MAY 27.1901. 11B1IEWBD 00T.zo. 1903.

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CLQMM No. 744,823. PATENTED Nov. 24, 1903.v

G..R. TUCKER & G. W. GODDARD. 'Y

GONGBNTRATING APPARATUS.

APPLICATION FILED MAY 2'?, 1901. RENEWED OGT. 20. 1903. N0 MODEL.

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PATENTED NOV. 24, 19GB. G. R. TUCKER & G. W. GODDARD.

GONGENTRATING APPARATUS.

APPLICATION FILD MAY 27, 1901. RKNEWED 00T. 20. 1903.

N0` MODEL.

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No. 744,823. PA'IBNTED NOV. 24,` v.1903. G. R. TUCKER & G. W. GODDARD.CONGENTRATING APPARATUS.

APPLICATION FILED MAY 27, 1901. RBNBWED 00T. 20, 1903.

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UNITED STATES Fatented November 24, 1903.

ATnnT ridete.

GREENLEAF R. TUCKER, OF BOSTON, MASSACHUSETTS, AAND GEORGE IILLISGODDARD, OF CONCORD, NEW HAMPSHIRE, ASSIGNORS OF ONE-THIRD TO EDWARDS.BEACH, OF BOSTON, MASSACHUSETTS.

CONCENTRATING APPARATUS.

SPECIFICATION forming part of Letters :Patent No. 744,823, dated.November 24, 1903. Appnootioo not Moy 27,1901. nonowoa ootoiiooI zo,1903. sorio1No.177.s1s. (No motor.)

[ all whoml t may concern;

Be it known that we, GREENLEAF R. TUCKER, residing at Boston, in thecounty of Suffolk and State of Massachusetts, and GEORGE WILLIS GODDARD,residing at Concord, in the county of Merrimack and State of NewHampshire, citizens of the United States, have invented certain new anduseful Improvements in Concentrating Apparatus, of which the followingis a specication, reference being had therein to the accompanyingdrawings.

Figure l is a view, partly in side elevation and partly in verticalcentral section, of one form of our apparatus embodying our in- Yvention, some of the pipinggbeing broken away for greater clearness.Fig. 2 is a side elevation of one form of our new concentrator orevaporator which forms part of the complete apparatus shown in Fig. 1.Fig. 3 is a top plan View of what is shown in Fig. l eX- cept that theconcentrator is shown in section on or at a line at 3 3 of Fig. 2, allthe concentrator above the belts being removed for greater clearness.Fig. 4 is a verticalsectional View of the refrigerating-pan at line 4 eof Fig. 3 looking in the direction of the arrow seen at saidsection-line. Fig. 5 is a sectional plan View at line 5 5 of Fig. 1looking down and shows details of the concentrator with rolls, belts,and Scrapers removed and shafts broken away for greater clearness. Fig.6 is asection al elevation of another moditied form of concentrator,some auxiliary parts beingin full lines. In this form of concentrator aplurality of belts are used, all the belts being in a common casing.Fig. 7 is a sectional elevation of a modified form of concentrator, someauxiliary parts being shown in full lines. In this form of concentratora plurality of belts are used, each belt being in a compartment byitself. Fig. 8 is a lengthwise sectional elevation of a modified form ofrefrigerating-pan combined with a refrigerating-agitatorinstead of witha rotary agitator, as in the preferred form. Said View is ou a line at S8 of Fig. 9 looking in the direction of the arrows seen at saidsectional line. Fig. 9 is a transverse sectional elevation of what isshown in Fig. 8 and istaken 'natural cows milk. sumption ofA condensedmilk are due toits enhanced keeping quality, its condensed form,

sumed to an enormous extent in most civilized countries of the world asa substitute for The popularity and conand to the fact that it can beeasily, economically, and safely transported and drawn upon as desiredwhen milk is needed away from the source of milk-supply. Itsdisadvantages are general inferiority to natural milk, due todeleterious or objectionable changes that it undergoes duringmanufacture, these changes mainly resulting from cooking and fromoverlong time consumed in the process of condensation. The color, odor,and taste of condensed milk are not the same as those of natural milk,and in the case of sweetened condensed milk the presence of an abnormalamount of sugar greatly restricts its range of usefulness. The method ofmaking condensed milk is essentially the same in all countries. Itconsists in evaporating milk to a thick consistency in a vacuum-panunder diminished pressure, whereby the water is evaporated at a muchlowertemperature than it could be in an open pan under normal pressure.Nevertheless the milk is injured in this process, owing to imperfectagitation, which permits particles of the milk to be overheated bycontact with the hot Walls of the evaporating-pan and also owing to theundue length ot' time required to complete the operation. Short time isa most important factor in a ,properprocess of producing condensed orconcentrated milk, as well as in producing many other food or beverageforming concentrates,

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condensations, extracts, and the like, not only in order to minimize theperiod of bacterial development or fermentation, but also in order toeconomize the labor and power required to produce the desired product.

The production of milk and other beverage and food forming concentratesinvolves the removal of most of the Water by a procedure that does notinjure physically or chemically the solid constituents of the milk, andby our apparatus there may be obtained a heatevaporated uncookedconcentrate of milk or other food-forming material, the concentratebeing largely sterilized by the heat applied in the step of evaporation.The concentrate may be preserved by combination with suitablepreservatives, such as sugar in the case of milk. When heat is employedto produce the evaporation, as it is in our apparatus, the principalfactors that influence the quality of the product are the degree of heatemployed and the length of time it is applied.

lWhen liquid is subjected to evaporation in an open pan, the rate ofevaporation depends on the extent of liquid-surface exposed, on thetemperature of the liquid, on the barometric pressure, and on thehumidity of the surrounding air. The rat-e of evaporation is greater thegreater the surface exposed and the higher the temperature of the liquidup to its boiling-point, where it is at its maximum and where it remainsconstant. When milk is evaporated, the rate of evaporation of theaqueous part thereof depends on the extent of surface exposed and on thetemperature to which the milk is heated; but in the case of milk theheat which may be employed to effect evaporation is restricted to atemperature that will not injure the milk solids, and that temperatureis determined to a considerable extent by the volume of milk to beevaporated-in other words, by the length of time the milk must besubjected to heat to attain its desired degree of concentration.

v In our present apparatus the milk or other volatilizable substance tobe evaporated is exposed in thin films or sheets to the action of anartificially-heated atmosphere operatively maintained in the form of acurrent by the means of a suitable blower or suction device operativelyconnected with the casing of the concentrator within which evaporationtakes place. By thus exposing the volatilizable substance a maximumevaporating-surface is secured, resulting in a corresponding rapidity ofevaporation.

By our apparatus the aqueous portion of the milk or other evaporablesubstance is not evaporated, as heretofore, directlyinto a normalatmosphere, but into the artificiallyheated atmospheric or gaseouscurrent to which the material in its sheet, spray, or comparable form isexposed, the current taking up water or other volatile matter and carry,

a'current of artificially-heated air takes up ature to which milk can beheatedv for the purpose of evaporation is limited to that temperaturewhich will not injure it. That temperature appears to be from about 70to 80 centigrade for small quantities for a short time and from 50 to60o centigrade for larger quantities for a longer time. We thereforeprefer to evaporate the milk at the latter temperature. That portion ofthe milk which is in sheet-like or sprayed condition is in practicingour process preferably maintained at from 50 to 60 centigrade duringevaporation; but the maintenance of this temperature of the milk duringevaporation is effected by the surrounding heated-air current, which forrapidity of evaporation should and may be from to 100 centigrade. Milk`subjected to the influence of from 90 to 100 centigrade in the ordinarymanner of heating or evaporating liquids would be quickly cooked orruined; but the milk in its sheet or'spray form on the belt is inconstant motion, andthe heated air is also in motion, and rapidevaporation takes place by virtue of the great capacity of heated airfor moisture. The moist air is removed as fast as formed, and a workingtemperature of from 50 to 60 centigrade of the milk in sheet-like oranalogous form, notwithstanding the surrounding air-current is from 90to 100 centigrade, is a resultant of the evaporation under the statedconditions and due to the cooling effect of the evaporation on the belt.The milk, therefore, is not overheated-that is to say, the seemingantagonism to milk of from 90 to centigrade of heat is reconciled underour process, because of this high degree of heat, which under normalconditions impairs the milk, reduces the temperature of the milk ornon-evaporable solids to from 50 to 60 centigrade, and the discovery ofsaid Tucker, stated in said pending application, that both the hightemperature, required question whether spores subjected to this IOO IIO

temperature can develop into full-grown organisms. If they can, thencomplete sterilization is possible by our method, because in that eventthe spores will be changed into fullgrown organisms, and the full-grownorganisms will be killed, wholly or in part, at the ,this method at atemperature substantially lower than 50O centigrade results in failure,owing to the multiplication of organisms and consequent coagulation,souring, peptonization, and other results of bacterial development. Inother words, a temperature of from 50 to 60O centigrade is a temperatureat which bacteria cannot multiply, and even though the same temperaturedid not partially sterilize, which it does, milk could still besuccessfully concentrated by this apparatus.

It is a coincidence in the process carried out by our apparatus, and afortunate one, that the temperature at which the milk can be evaporatedwithout deleterious physical or chemical change is a temperature whichprohibits the development of bacteria, which kills most of them, and atthe same time is a temperature which permits a considerable rate ofevaporation, which rate may be enormously increased by raising thetemperature of the evaporatng and water-removing current.

The criterion of the goodness of condensed milk is the exactness withwhich it when diluted with a definite amount of water corresponds towhole milk. The relation of butter fat and of solids not fat should bearthe same relation to each otherin condensed milk that they do in wholemilk. The color, odor, and taste of the condensed milk should correspondwith those of whole milk, and the condensed milk should be such thatwhen properly diluted with water the product cannot be distinguishedfrom whole milk and be from a chemical point of view up to the standardset for whole milk drawn directly from the cow. It is safe to say thatno coudensed milk in the market fulfils these conditions. The presentcondensed milks are deicient in solids for the degrees of dilutionrecommended. The relation therein of fat to solids not fat is notcorrect. They are especially deficient in fat, and their color, odor,and taste are more or less objectionable.` Diluted with water they donot correspond to whole milk, either chemically or physically. AbsoluteeXactness in a condensed milk is perhaps an impossibility; but it ismuch desired by producers and consumers.

From a chemical point of view the milk constituent which probablyundergoes the most essential change when whole milk is concentrated isthe fat. Decomposition products of fat in any considerable amount areoffensive alterations of the constituents of milk. Changes in thecasein, albuminoids, dac., are not particularly objectionable; but thesum total of effect when whole milk is concentrated by customary methodsis a product changed chemically and physically from the normal to agreater extent than is desirable.

In using our apparatus for the concentration of milk we prefer tooperate on milk from which the fat has been removed--a e., on skimmedmilk. To the final skim-milk concentrate produced there is preferablyadded the proper amount (usuallya statutory requirement varying in thedifferent States) of butter fat in the form ofcream, by which procedurethere is obtained a finished condensed milk more nearly approaching thestatutory standard than by the concentration of whole milk itself; butwhole milkmay be treated in our apparatus, if desired. The heatedcurrent used to induce the evaporation and to arrest bacterialdevelopment may be any suitable m oisture-absorbing gas-such asatmospheric air or carbonio-acid gas, for example. By apparatusembodying our invention we are able to concentrate whole or skim-milk,fruit-juices, infusions of malt, beef, dac., the concentrates beingcharacterized by natural taste and fiavor.

Inasmuch as shortness of time is a very important factor in theproduction of alimental concentrates in accordance with either saidmethod or with this present invention, we sometimes prefer in the caseof milk, especially in some climates and under some conditions, to havethe concentration supplied with what may be called a "partial"concentrate obtained from :so-called cold-process refrigerating andcentrifugalizing apparatus; but we have successfully concentrated bothwhole and skim milk by beginning its treatment in the concentrationitself without first passing the milk through so much of theherein-described apparatus as is prior in its operation to the operationof the concentration itself.

In the drawings illustrating the principle of our invention and the bestmode now known to us of applying that principle, A is a weighing-can,and ct the scales therefor. Can A discharges through its outlet d',which is controlled by a valve a2, into a trough a3, which dischargesinto a receptacle A', preferably provided between its ends with a screena4. The bottom ai of the receptacle is inclined from below the trough a3-to its outlet end, where the outlet-pipe a6 leads, in this instance, toa tempering-box A2, the outlet-pipe o. of receptacle A' being providedwith a valve al. In lieu of the temperingbox A2 a pasteurizermaybe used,yif so desired. From the tempering-box A2 an outletpipe cts leads toaseparator A3, provided with the usual cream-ejector a", the cream'being thereby thrown into trough alo, which dis- IOC IIO

sys

charges on the corrugated cream-cooler A4, whence the cream isdischarged into the cream-can A5. The corrugated cream-cooler A4 isprovided with the usual water-escape conduit 0.41 and the water-inletconduit (L42.

All the foregoing parts in the arrangement described are old and wellknown, and too well known by all skilled in the dairy art to requiredetailed description.

The skimmed milk is thrown upwardly from the separator A3 through theskimmed-milk conduit 01.43 in the old and well-known way. In practice,as is well known, the skimmed milk may be ejected upwardly from theseparator for a distance ofV eight or ten feet. In carrying out ourinvention in the mode hereinafter illustrated the skimmed-milk conduitcl3 is carried back and forth through the pipes a, which are connectedby return-bends c45 0.45, the skimmed-milk conduit L13 Ahaving anexterior diameter which is less than the interior diameter of the pipes0.14 rtl4, through which latter pipes a suitable refrigeratinggas orother suitable refrigerating medium is circulated, so as to cool, butnot congeal, the skimmed milk while it is traveling to therefrigerating-pan A*. Skimmed-milk conduit 0,43 Opens above the pan, soas to discharge therein. The cooling apparatus, composed in thisinstance of the pipes @L14 and returnbends c45, may be connected in anysuitable manner with any suitable supply source of refrigerating medium.The refrigeratingpan A* is mounted within a box A6 and is preferablysurrounded with a coil am within box A6, the coil conveying a suitablerefrigerating medium from any suitable source of supply, so as tocongeal the skim-milk in pan A*. An outlet-pipe a is provided for boxAG, so as to lead off any moisture that may accumulate therein.

It is -of practical importance that the refrigerating-coil als shouldnot pass over the skim-milk in the refrigerating-pan A*,because if suchwere the case then the moisture evaporating from Ithe skimmed milk inthe pan would congeal on the pipes in the form of frost orsnow, and thesame would frequently drop off into the milk in the pan and contaminateand dilute the skimmed milk therein. Consequently we prefer not toexpose the milk to refrigeration at its exposed surface.` Simultaneouslywith the congelation of the skim-milk in pan A* it is agitated so as tobreak it up into small portions or flakes, and in order to agitate theskim during congelation and so prevent it from freezing solid, anagitator-shaft als is carried through the box A6 and pan A* and providedwith a rotary agitator al* within pan A*.

The vupper end of agitator-shaft u.1S is journaled in a fixed bearingd20, and the shaft is driven in this form of our invention by thecrank-rod a24,connected with a crank @won the agitator-shaft. Shaft alshas another bearing in a transverse strut 8 at the upper part of.threaded plug w23.

masas pan A*, through which strut ythe shaft passes upwardly out of panA*.

The bottom of pan A* is provided with an outlet-port which is closedbyasuitable cover or stopper, shown here in the form of a Plug (L23screws into an internally-threaded sleeve @24, fixed on the innersurface of pan A*, which it surrounds. Plug w23 is fast on the threadedrod (125, which passes from the plug downwardly through the bottom ofchamber (126, where it has a bearing in theinternally-threaded boss a,so that the shaft c25 is centered. By turning shaft c25 in one directionor the other the plug a2* is moved to open or close pan A*. To removeany milk that may have congealed on that part of shaft als which iswithin pan A*, as well as on the agitator alg, the shaft als and themembers of the agitator are preferably made hollow, so that steam may beadmitted to warm up the shaft and agitator, and thereby remove anycongealed milk thereon. The steam may be admitted byeonnecting at (1.28any suitable supply-pipe coming from a source of steam-supply. ChamberL26 communicates with the discharge-conduita29, so thatwhen the plug@23is open the congealed but broken-up milk will flow from therefrigerating-pan A* into the basket centrifugal machine B. Thecentrifugal machine B (shown in the drawings) is provided with the usualbasket b on the vertical shaft b and rotates therewith. In the operationof the present apparatus the congealed milk is discharged into thebasket b, and as the basket rotates the partiallyconcentrated milk isthrown outwardly by centrifugal force through the perforations b2 of thebasket into the chamber b3, whence it flows through the central apertureb4 into the chamber b5,which is provided with any desired number ofoutlet-conduits h6, in this case two in number. In the present instancewe inclose the centrifugal machine B in asurrounding casing B and placewithin the casing B a refrigeratingcoil B2,of any desired form, thepurpose of the refrigerating-coil within the casing B' being to maintainthe congealed milk at or slightly below the freezing-point. It isimportant that the temperature of the congealed mass in the centrifugalmachine should not at any time during the operation thereof rise abovethe freezing-point, for in that levent the congealed mass will begin tomelt, and any melting will result in a dilution of the product, whichescapes through the outlet conduit or conduits b, and such dilutionwould materially interfere with the rapidity with which concentrationwould be effected and with the economical operation of the machine.Outlet-pipe h6 for the discharge of the partiallyconcentrated milk fromthe centrifugal machine leads downwardlyv into a receivingtank D, Afromthe lower end of which a discharge conduit cl is formed into a coil Dwithin the casing D2.

The conduit d is pro- IOO IIO

vided with a valve d' between vtank D and casing D2, the conduit dthence leading, preferably, into an observation-receptacle D3, whereinit discharges. A valve d2 is pro` vided between the casing D2 andreceptacle This receptacle D3 may be made of glass,` if desired, or ofother material and provided; with a window for convenient observation ofthe temperature and the material in the re` ceptacle Das it ilowstherethrough. A ther-I mometer T is preferably introduced into thereceptacle, with its stem extending upward through the stopper or covercl3 thereof. The

material in receptacle D3 flows therefrom manner as conduit d is coiledat D in casing D2,) and leads thence to an auxiliary closedobservation-receptacle 5, wherein is asecond thermometer T'. Fromreceptacle 5 a conduit 6 leads into a flushing-pipe 7 within the casingof the concentrator F, for a purpose described later on.

The object of our invention in respect of the concentrator is to providea maximum rate of evaporation without subjecting the milk to atemperature which will alter or impair its natural quality or davor, andWe hereinafter point out an important discovery in this connection.

`Referring to the construction of the preferred form of our newconcentrator,fis a closed casing within which, near the upper partthereof, a plurality (preferably) of rollers f' are mounted with theirjournals f2 in suitable journal-boxes f3, secured to the oppositeoutside walls of the casing. At the bottom portion of said casing thereis another series of rollers f4, which are respectively staggered withrespect to the upper rollers f', the journals f5 of the lower rollersbeing mounted in suitable journal-boxes f6, fast to the oppositeoutsides of the casing. Near that end of casingf into which the conduitd4 leads and toward the bottom of the casing there is a transversetrough or receptacle F' for holding the milk (or other material) to beconcentrated. Receptacle F' isin parallelism with the rollers f' and f4.The inlet-conduit d4 discharges over this trough F', and roller f7 ismounted within the trough with its journais]e8 mounted in bearings fi onthe opposite outsides of the casing. A transverse roller flo isjournaled at the upper part of casingf near the receiving end of theconcentrator, and a transverse roller f is similarly journaled at thelower portion of the concentrator, near the receiving end thereof.Toward the discharge end of the concentrator a doctor]E12 is mounted oncasing f in contact with the inner side of an endless belt, and

other doctors j3 are similarly mounted to engage the other side of thebelt. All the rollers mentioned support and guide an endless belt F2,which is caused to travel over the rollers by power applied in anysuitable manner to one or more of the journals of the rollers. In thisinstance power is applied to a journal f8 of the roller f7, whichrotates within receptacle F', the journals being extended beyond theoutside of the casingfand provided with adriving-pulleyf. Thisjournal isalso provided with a sprocket-wheel fm, whence a chain f15 extends to asprocketwheel on the next roller-journalfs,which,with the otherroller-jou rnals f5 on the same side of the casing, is provided withsprocket-wheels, all connected and drawn by a sprocket-chain fw. This isone of many well-known mechanical arrangements by which belt F2 iscontinuously driven to lift by adhesion the substance in the trough andcarry it up and down over those rollers which are between the trough andthe discharge end of the concentrator, the substance on the belt beingremoved to a great extent at the discharge end of the concentrator byany suitable means-such as the described doctors, for example-into areceiving-receptacle F3, which preferably is of a length equal to thewidth of the concentratorand removable therefrom through a doorway f.After passing the doctors the belt is led under a roller flS and thenceunder roller f, whence it goes over the roller flo and down to thetrough F'. To prevent droppings from the belt or rollers falling on thebelt as it runs, as indicated by arrow, from roller f7 to roller fls, Weprovide a shield fm, which is a little wider than the belt and which isconveniently hung on the journals of the rollers f4, such journalspassing loosely through the holes in the boss fm, which extend upwardlyat opposite sides of the shield. The opposite end portions of shield f19incline upward and outward at fm, so that droppings from the upperrollers f' or from the belt will run downwardly and be caught in thetransverse troughed portions f22 of the shield, the side margins ofwhich project over the gntterfzg, that extends clear around the innerside of casing f and is inclined so as to discharge into trough F', asat f24 f. Concentrator F is provided at its bottom portion with agas-inlet pipe F4,'which extends around the casing and provided with anumber of perforations fi for the introduction of heated atmospheric airor other gas within the casing f during the concentrating operation.During the concentrating operation the hot air introduced therein ismaintained in current form by any suitable device, such assuction-blower G, the construction of which is too well known ltorequire description. The inlet-conduit g of the suction-blower is ledinto the casing f, preferably at the upper side thereof, and the hot airis drawn through the concentrator F by the operation of thesuction-blower, so

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that the endless belt travels in a continuous current of hot atmosphericair or other suitable gas,and the milk (or other material) supplied totrough F' is continuously removed from the trough into the chamber ofthe casing in sheet or film-like form on the surfaces of the belt.

In order to prevent solidification and charring of the milk which mayspatter on the side Walls of the casingf, the auxiliary parts l, 2, 3,4, 5, and 6, above referred to, are provided, the auxiliarysupply-conduit 6 leading through the top of casingf into the horizontalflushing-pipe 7, Which extends around the casingf, inside thereof, andis provided with a number of perforations f2s, through which the milk(or other material) so introduced into the' conduit or pipe 7 'flows`out and trickles down the vertical side Walls of the casing, formingpractically a continuous sheet or film of milk on the inner surfaces ofthe side walls, Where, like the films or sheets of milk (or othermaterial) on the belt, itis exposed to the evaporating action of' thehot gaseous current traveling through the casing. The gutter f23 catchesthe downflow, which thereby flushes the inner side of the casing, thedownflow, of course, being of the same material as that being treatedand escaping from gutter f by the escapes f24 into the trough F', Whereit commingles with the contents thereof and is again subjected to theaction of the belt and gaseous current. This constant return of thedoWnfloWing flushing 'material (milk or other liquid) into the mainportion of the material being concentrated greatly increases therapidity of the concentration of the Whole mass, because suchdownflowing lushing material is itself more or less concentrated inconsequence of the evaporation to which it is subjected While flowingdown the inner sides of the casing.

The various parts herein described through which the milk or otherliquid passes into the centrifugal B, together With the centrifugal,constitute one kind of a supply source for the evaporator orconcentrating apparatus defully described.

A `gage f2? is conveniently mounted on the outside of casingf, with itsstem leading into trough F' in order that the supply to the trough maybe shut olf before too much material accumulates therein.

The heated gas-inlet pipe F'1 draws its heated supply from any source,vsuch as through the heater F5.

In the drawings We have shown many valves to Which no particularreference has been made, although some'of them have been described. Thenumber and arrangement of the valves in the different parts of theapparatus will in practice depend largely on the preference of theconstructor or user.

It will be obvious to all mechanics that different factors of theapparatus may be differently constructed and arranged and that thedimensions ot' the various parts may be greatly varied, according to thenature of the material to be concentrated, as well as to the quantitywhich it isdesired to concentrate. It is our intention, however, that,as a general rule, the lapparatus shall be constructed on a large scale,so that in the case of milk, for example, all the milk brought to adairy may be speedily reduced to the form of a thick concentrate, whichis more economical for storage or transportation than milk in itsordinary legal form.

When all the valves ot' the system are open and the agitator,centrifugal machine, and concentrator are all in operation, the WorkWill continue, although it may be desirable now and then to stop thesupply to the trough or receptacle F' in the concentrator. We desire itto be distinctly understood that, if desired, the material to beconcentrated may be put directly into the trough F' without any priortreatment, for the process of concentration isvso rapidly andefliciently performed by the concentrator alone that for many uses andunder many conditions no auxiliary apparatus is necessary. In makingthis statement We of course include as a part of the concentrator themeans for supplying i the chamber thereof with a current of hot gas. Anydesired material may be used for the belt F2, and while We have foundordinary canvas to be efcacious We prefer to use a Woven-Wire belt, inthe interstices of which the material to be concentrated is caught dur,- ing the travel ot the plate. The number of rollersf" and f4 whichare used Will depend very largely upon the desired capacity of theconcentrator, and, generally speaking,we prefer to use a plurality--infact, as many as practicable-ot the upper rollers f' and as many aspossible of the lower rollers f4 in order that the maximum belt-surfacemay be obtained for exposing the material in its adhering sheet or filmlike form to the hot'current which rushes over and past it. The degreeofheat employed must be varied for dif- IIO ferent materials, and. it isto be remembered ferent parts of our apparatus are to be provided withdoors, manholes, and the like, so that the interior of the differentparts may be reached and readily cleansed. In order to thoroughlycleanse the apparatus as a Whole, We may connect its several parts A',A2, A3, A5, A, B, B', D, D3, 2, 5, and '7 With a Vlivesteam pipe, sothat through suitable connections of the several parts to the saidlivesteam pipe live steam may be admitted therein and pass through thevarious connectingcondnits for the sterilization and cleansing of theapparatus as a whole. The steam-pipe may be conveniently led from theboiler of the engine used for driving the apparatus. 'Ihe steam-pipe forthis purpose is not shown, because it will be readily understood bymechanics Without particular description.

In Fig. 6, showing a modification ofthe concentrator, a series ofindependent receptacles or troughs J are mounted within theconcentrator-casing and connected at their bottoms by a common inclinedpipej, provided with suitable valves/j. lWithin each trough a roller jgis mounted, and within the casing, near the top thereof, there is aseries of rollers js, each of the upper rollersj3 being directly over arollerj?. Over each opposite roller jg and js a beltjLl passes, so thatthe concentrator-casing contains a pluralityof belts. The troughs .I areat different levels, so that the material concentrated iu the firsttrough may tloW into the second trough and be therein furtherconcentrated, and so on to the last trough.

In Fig. 7 another form of concentrator is shown, which is made up of aseries of independent glass casings each containing a trough K, a valvek, rotating roller k', and an upper roller 7a2, with a belt passing overboth rollers. The several independent casings are each connected to acommon suction blowerpipe 7e3, the troughs in the several boxes are atdifferent levels, and inclined pipe Ztl leads from the higher trough tothe next lower trough, and so on from trough to trough, as in themodification described in the preceding figure. The hot-gas-inlet pipeZ155 is provided with `perfor-ations k6, and each of the independentcasings is imperforate between the casings, which are severally markedk7.

In Figs. 8 and 9, showing a modification, we show a refrigerating-panand agitator of a construction Widely differing from that shown in ourpreferred form of apparatus; but the two forms have this in common, thatthe agitator for each pan operates so as to prevent the congelation of athick mass at the sides of the agitator. It is very important to preventthe formation of the thick mass of the material operated upon in therefrigeratingpan and out of the field of operation of the agitator,because such a mass will frequently tend to sour or ferment and so spoilsuch of the contents of the pan as is being constantly agitated by themovement of the agitator during the time that the agitated mass is beingsimultaneously congealed and broken up into flake-like form. In thismoditication the refrigerating-pan L is provided with a gate ZX and ismounted on a car Z, that may be moved along tracks Z', leading into theinterior of the refrigerator M, through a passage which may be sealed bysuitable means, such as a double door m. Parallel with the track is apartition charge therein when the car is within the refrigerator. Theagitator is designed to move lengthwise the pan L, and consists of areciprocating rod o and rake o', pivotally secured thereto, the rodentering the refrigerator through a suitable stuffing-box m5 in the wallm6 opposite t-he door fm, and at a point above the top of the pan. Thehead 020i' the rake o at right angles to the rod o extendsacross the panL and is provided with numerous tines o3, fast in the base of a bar 04,

.triangular in cross-section, the apex of the bar being in contact Withthe bottom of the pan, as shown in Fig. 8. At each end of the head ofthe rake and lying above the adjacent top edge of the pan is a round rodo5. Near each end of the pan L a pair of brackets Z2 is secured to andabove the sides Z3 of the pan L for the purpose of supporting inclinedWays Z4, each waybeing pivotally secured to itsrespective bracket andhavingits free end resting on the top of the side Z3 of the pan, as atZ5. The rod 0 is reciprocated by any suitable means-as, for example, bya crank and connecting-rod o6. To remove any milk that has congealed onthat part of the agitator within the pan, the agitator o' is madehollow, so that steam may be admitted by connecting thereto, as at o7,When desired, a suitable supply-pipe coming from a source ofsteam-supply. It will now be plain that in the movement of the agitatorfrom one end of the pan to the other the round rods o5 on the head o2 ofthe rake will come into contact with a pair of inclined Ways Z4 Z4, rideup the same, as shown in dotted lines in Fig. 8, and then the rake 0' ofthe agitator Will drop of its own weight close to the end of the pan Land then be drawn along the bottom of the pan in an opposite directionunder the free ends of said ways Zl Z4 at Z5 Z5, come into contact withthe other pair of inclined Ways, Z4 Z4, ascend the same, then drop, passunder said Ways, and repeat the first operation, the agitator thuspreventing the collection of a thick mass of material operated uponfrom. collecting at the ends and sides of the pan,

While our said invention is embodied in the form herein shown anddescribed, it Will be understood that we do not limit ourselves to anyparticular form of apparatus, it being obvious that many changes andmodifications may suggest themselves to any one skilled in the art.

What We claim is l. In concentrating apparatus, the combination of aclosed casing a gas-inlet port and IOT IIC

a gas-outlet port with a receptacle, within the casing, for liquidmaterial to be concentrated; a device forcontinuously removing from thereceptacle into the chamber of the casing, sheet-like portions of saidliquid material; means for creating and maintaining a current ofgasthrough the casing; means for removing concentrated material from saidremoving device, means for flushing the side Walls of the casing; andmeans for returning the flushing material into the receptacle.

2. In concentrating apparatus, the combination of a closed casing havinga gas-inlet port and a gas-outlet port with a receptacle, within thecasing, for liquid material to be concentrated; a device forcontinuously removing from the receptacleinto the chamber of the casing,sheet-like portions of said liquid material; means for creating andmaintaining a current of suitably heated gas through the casing; meansfor removing concentr-ated material from said removing device and meansfor flushing the side Walls of the casing.

3. In concentrating apparatus, the combination of a closed casing havinga gas-inlet port and a gas-outlet port with a receptacle within thecasing, for liquid material to be concentrated; means for continuouslyremoving from the receptacle into the chamber of the casing sheet-likeportions of said liquid material; means forcreat-ing and maintaining acurrent of gas through the casing; means for removing concentratedmaterial from saidremoving device; and means for flushing side walls ofthe casing. l

4. In concentrating apparatus, the combination of a closed casing havinga gas-inlet port and a gas-outlet port with means for creatmasas ing andmaintaining a gas-current through the casing; a receptacle, Within thecasing, for material to loe concentrated; a series of upperguide-rollers Within the casing, near the upper portion thereof; aseries of guiderollers within the casing, near the lower part thereof; aroller within said receptacle; an endless belt mounted on and supportedby said rollers; means for traveling said belt; means for removingconcentrated material from said belt and means for iiushing the sidewalls of the casing.

5. In concentrating apparatus, the combination of a source of supply ofliquid material to be concentrated with a closed casing having agas-inlet port and a gas-outlet port; a receptacle, within the casing,for liquid material to be concentrated; a device for continuouslyremoving from the receptacle into the chamber of the casing, sheet-likeportions of said liquid material; means for creating and maintaining acurrent of gas through the casing; means for removing concentratedmaterial from said removing device; means for flushing the side walls ofthe casing; means for returning the flushing materialinto thereceptacle; and, intermediate the casing and said source of supply, twosets of supply devices, each substantially as described, and onedischarging into said receptacle and the other feeding into the flushingmeans.

In testimony whereof We affix our signatures in presence of twowitnesses.

GREENLEAF R. TUCKER. GEORGE WILLIS GODDARD.

Witnesses:

M. E. COVENEY, E. A. ALLEN.

